analogReadResolution()

[Analog I/O]

描述

Sets the size (in bits) of the value returned by analogRead(). It defaults to 10 bits (returns values between 0-1023) for compatibility with AVR-based Arduino boards.

The 86Duino boards have 11-bit ADC capabilities that can be accessed by changing the resolution to 11. This will return values from analogRead() between 0 and 2047.

語法

analogReadResolution(bits)

參數

bits: determines the resolution (in bits) of the value returned by analogRead() function. You can set this 1 and 32. You can set resolutions higher than 11 but values returned by analogRead() will suffer approximation. See the note below for details.

回傳

無

注意

If you set the analogReadResolution() value to a value higher than your board’s capabilities, the 86Duino will only report back at its highest resolution padding the extra bits with zeros.

For example: using the 86Duino with analogReadResolution(16) will give you an approximated 16-bit number with the first 11 bits containing the real ADC reading and the last 5 bits padded with zeros.

If you set the analogReadResolution() value to a value lower than your board’s capabilities, the extra least significant bits read from the ADC will be discarded.

Using a 16 bit resolution (or any resolution higher than actual hardware capabilities) allows you to write sketches that automatically handle devices with a higher resolution ADC when these become available on future boards without changing a line of code.

範例程式碼

void setup() {
  // open a serial connection
  Serial.begin(9600); 
}
 
void loop() {
  // read the input on A0 at default resolution (10 bits)
  // and send it out the serial connection 
  analogReadResolution(10);
  Serial.print("ADC 10-bit (default) : ");
  Serial.print(analogRead(A0));
 
  // change the resolution to 12 bits and read A0
  analogReadResolution(12);
  Serial.print(", 12-bit : ");
  Serial.print(analogRead(A0));
 
  // change the resolution to 16 bits and read A0
  analogReadResolution(16);
  Serial.print(", 16-bit : ");
  Serial.print(analogRead(A0));
 
  // change the resolution to 8 bits and read A0
  analogReadResolution(8);
  Serial.print(", 8-bit : ");
  Serial.println(analogRead(A0));
 
  // a little delay to not hog serial monitor
  delay(100);
}

參考

• [Example] Description of the analog input pins
• [程式語法] analogRead()

語法參考主頁面

86Duino 參考的文本是根據 Creative Commons Attribution-ShareAlike 3.0 License，部分文本是從 the Arduino reference 修改的。 參考中的代碼示例已發佈到公共領域。